Replies

1. 
   Jfrostjr | Feb 29, 2008 06:40pm | #1

   I have had no trouble with my 4" ducts over the past 8 years. I had a 1 HP Penn State DC and then upgraded to an Oneida Dust Gorilla. That dude really pulls the volume. I installed grounding wire, but I doubt it is all connected now - or necessary.

   Frosty

   "I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922

2. 
   blewcrowe | Feb 29, 2008 10:01pm | #2

   Works okay. Just put in that ground wire like they recommend.

1. 
   pita | Mar 01, 2008 08:09am | #3

   bare copper wrapped around the outside of the pipe or on the inside?

   So when you are installing the PVC do you use 90 degree elbows at the corners or 2 45 degree elbow, about 4 to 8 inces apart to ease the corner (assuming you have the room)  AND lastly, if you do not use PVC cement does it affect air flow?  I'd like to be able to take it apart.

   Thanks - Scott

1. 
   DonC | Mar 01, 2008 08:22am | #4

   Published articles have stated that it's not necessary to ground a typical home shop. There is debate on this.

   A simple solution is to drill 3/16" holes about every 2 feet thru all your pipes. Attach a clip and pop rivet in all the holes from the outside. The clip is on the outside of the pipes. Run copper wire thru all the clips. Static will discharge as it passes the pop rivet heads that protrude on the inside of the pipe. This is fast and works. You can just simply run the wire past all your vac gates without the hassle of running the wire internally and having to wire up gate jumpers.

   This method is analogise to touching metal often/periodically when you run a shope vac. You don't get shocked.

1. 
   pita | Mar 01, 2008 08:42am | #5

   That's a fantastic idea, I know what a rivet is but can you define what you mean by a clip, a paper clip which is used to run the copper thru?

1. 
   DonC | Mar 01, 2008 06:41pm | #7

   http://www.radioshack.com/family/index.jsp?cp=2032058.2032231&categoryId=2032283&pg=4

   Look at part 64-3028. My "clip" looks like this only is aluminum. Any metal part shaped like a figure 8 with 2 holes would work too. One hole for the pop rivet and one for the wire. Make sure the hole in the "clip" is bigger than the rivet will expand in the PVC and not in the clip.

2. 
   pita | Mar 01, 2008 07:33pm | #8

   I'm liking this idea more&more!

2. 
   graphguy | Mar 01, 2008 05:56pm | #6

   Being a scientist, I always appreciate the finer details of a subject, but mostly marketing hyperbole gets in they way of reality.  Too much detail outside the laboratory or college classroom on theory just gets in the way of a plain workable solution.  With that said, go ahead and read about static pressure, etc etc, but in the end focus on the simple idea, does it move enough wood for my level of woodworking activity? Using PVC does it fine and in a very cost effective manner.

   Edited 3/1/2008 9:58 am ET by graphguy

2. 
   dondownunder | Mar 02, 2008 04:22am | #10

   If you detect air leakage at the joins duct tape them, easy to remove if you want to change things around, which you will.

   The radius of an elbow should be about 1.5 times the diameter of the pipe, ie for 4" pipe a centerline radius of 6" is an ideal minimum . Down here sewer pipe (heavy wall thickness) PVC is 1.5 X but stormwater (thinner wall) is much tighter.

   Don

3. 
   blewcrowe | Mar 03, 2008 04:26pm | #16

   It looks as if you're getting lots of capable advice so I'll leave it at that.

   And yes, there's controvery over this static electric thing, but I'd address it if I were you.

3. 
   myxylplyk | Mar 02, 2008 01:55am | #9

   The concept of a static charge igniting the sawdust while traveling in a PVC dust collection system comes up a lot.  On the face of the discussion it make sound logical sense. After all, static charges seem to be on PVC pipe all the time anyway, so the logic flows toward the assumption that the moving particles will build more static more quickly, thus increasing the chance for ignition.

   Now look around.  There are thousands of hobbiest and "professional" woodworkers in this country, using PVC dustcollection systems.  With practicaly every other possible safety disaster showing up within this group, I have never seen one cast of spontaneous ignition/combustion from static.

   In my opinion, you have a much greater chance for ignition of the dust collector contents from "sucking up" loose pieces of ferric metals into the dust collection system and making sudden impact on a metal impeller.  I don't worry about static, only screws and nails.

    

4. 
   Don01 | Mar 02, 2008 06:53pm | #11

   Use the lighter weight S&D pipe not the Schedule 40 wall thickness

   Pros
   - cost over reinforced metal
   - availability
   - you can make you own fittings if necessary - Y's
   - Clean outs are standard S&D fittings.
   - Joints can be easily screwed and taped for easy disassembly if required. ( If you plan for a plug up and it doesn't happen great, if you don't plan and it happens, you may find your self saying bad words :-) )

   Cons
   - Over 4" are harder to find (The dust collection industry continues to sleep on this one)
   - Cannot ground entire piping system*

   Static.
   *From what I have read, you can not effectively PVC will hold a localized charge. You might ground point A, but point B still holds a charge. Running wires inside or outside of the pipe does nothing because the charge is in the pipe. Wrapping some copper wire around the outside might help reduce the instances the you personally get the odd zap but no guarantee.
   Most setup involving rigid pipe have the pipe out of the way as opposed to the flex hose that is moved between machines, so the chances of you getting repetive shockes is minor.

   I regularly vacuum up the shop using a piece of flex and quite often see sparks going from the hose to the machines. No fire, no explosion.

   Don

1. 
   saschafer | Mar 02, 2008 08:47pm | #12

   "Running wires inside or outside of the pipe does nothing because the charge is in the pipe."

   Strictly speaking, the charge is on the surface of the pipe (both inside and out). It has occurred to me that you could bleed this off by painting the pipe inside and out with conductive aluminum paint, but I've never heard of anyone doing that, and I doubt that it's worth the trouble, except to avoid being zapped when you touch it.

   -Steve

    

    

2. 
   pita | Mar 03, 2008 07:53pm | #17

   thanks!

5. 
   flairwoodworks | Mar 03, 2008 02:21am | #13

   For attachment to portable tools or cleaning up dust with an attachment, Polyurethane is FAR SUPERIOR in flexibility.

   Chris @ flairwoodworks

    - Success is not the key to happines.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

6. 
   Dorsett | Mar 03, 2008 07:44am | #14

   I started with pvc, for all of the reasons mentioned in this thread.

   Then I switched to metal. For me its easier to work with, and there are more six inch connectors and pipes. I also obssessed about static electricity.

   Before I switched I was about to apply a line of aluminum tape, same location inside and out, drill holes through pipe and tape, attach through bolts, connect all bolts with wire, and ground the wire. I've heard this works in commercial shops, and eliminates all shocks.

   Dorsett

7. 
   Telemike | Mar 03, 2008 08:05am | #15

   4" PVC works fine. Don't worry about grounding it - you're only grounding the wire or ground point anyway because PVC does not carry charge along the surface to the wire. When I first started using the PVC system, I periodically sprayed some sort of laundry static preventer into the system to kill the charge. Then I quit and haven't worried about it for a long time.

   Some advice: Don't glue the joints. Push the pieces together and use two or three self drilling screws to hold the joint together. Then, you can disassemble later to change the system or to rod out obstructions.

   Don't use a floor sweep or use the hose as a vacuum. You'll get slivers and short pieces stuck crosswise in the line that will collect debris and plug the line up like a gourmet's arteries.

   Make you own blast gates. Use blades with 4" holes that pass through the gate rather than blades that go into pockets. The pockets will fill with sawdust and you'll not be able to close the gate.

   Use a BIG HP collector so you really don't have to worry about a little leakage. It's a lot easier than eliminating all leakage.

8. 
   TampaTom | Mar 03, 2008 08:02pm | #18

   Concerning static in PVC, here are some resources:

   http://www.rockler.com/blog/index.cfm?commentID=44

   http://www.waterfront-woods.com/Articles/Electricity/static.htm

   http://www.woodcentral.com/articles/shop/articles_221.shtml

   Uhhh, the resources are all over the place... Anyone want to hazard a guess?

   Tom Iovino

   Tom's Workbench

   http://tomsworkbench.com

1. 
   Buster2000 | Mar 03, 2008 10:37pm | #19

   I think Rod Coles article is the best referenced.  The rest reference dust explosions, but don't seem to have any record of any.  Until someone on a forum can step forward and say "My PVC collection system exploded" or until I meet someone, I'm not going to buy that PVC is a huge danger.  There is just too much rumor evidence, I believe this will go down as one of the big myths of woodworking.

   One thing all the articles do point towards is that you can NOT ground the PVC.  So the idea of wrapping wire is for comfort, not safety.

   For what it's worth I'm not a fan of PVC, been shocked a few too many times.  I'm in a new shop now, so I'm using the single machine connection until I'm happy with the setup.

   Buster

1. 
   Don01 | Mar 04, 2008 01:15am | #20

   Good reference Buster.
   I'll throw in his link.
   http://home.comcast.net/~rodec/woodworking/articles/DC_myths.htmlHe notes that there is a far greater danger in the dust pile on the floor or the dust swirling about in the filter bag right at the collector!Don